In vitro investigation of intra-canal dentine-laser beam interaction aspects: II. Evaluation of ablation zone extent and morphology.

Laser endodontic tips appear to provide a promising alternative to available treatment modalities in the field of endodontology. With the shortcomings in published results regarding the intra-canal behavioural aspects of those tips, it was the aim of this study to investigate the extent of the intra-canal ablation zone and the pattern associated with those tips. Ninety intact extracted bovine teeth were used to prepare mid-root testing cylinders. The samples were divided into three groups (A, B, C), corresponding to the tip diameters. Each group was further subdivided to be irradiated at three different power settings (1500 mW, 1750 mW, 2000 mW) with an erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser with a 65% water to 35% air ratio. Collected data were subjected to analysis of variance (ANOVA) and the Tukey test. At a chosen significance level of alpha = 1%, no statistical difference was found among the groups (P > 0.01). The results suggest that shortening of the estimated working length is mandatory for the use of those tips within the canal, and that, provided that certain measurements are used for intra-canal laser ablation, this is a secure mode of treatment. Further investigation and system improvement will be required for more satisfactory results.